Problem to solve

The diff, commit list, and pipelines tab usability is decreased by having a long description and merge widget above them all the time because means the top of the page doesn't actually show what I am trying to look at.

Recent user testing of file-by-file diff navigation ux-research#341 (closed) included this change, and was positively received. Although questions about the file-by-file navigation remain, adjusting the navigation tabs was well received.

Proposal

To provide more predictable and easy to find navigation within a merge request, and to provide greater focus in each area of the merge request:

move the merge request navigation tabs above the description

only show the description and merge widget on the Overview tab (replacing the discussions tab)

Since early research was very positive, we are confident that this deserves maximum exposure:

Add a feature flag, off by default, without a need for the user preference. We can then progressively enable the feature on GitLab.com.

Add an explanatory popover (see image below) with a button to dismiss (saved as a cookie?) and a link to an feedback issue.

To collect feedback, we can publish a blog post that links to the feedback issue and share it internally and on social media.